Emotional Problems in Parkinson's Disease

An Underrecognized Problem

Depressed man
Image Source / Getty Images

Emotional problems have been widely published on in Parkinson’s disease. While this may partially result simply from having a serious illness, emotional changes also likely result from nervous system changes due to the disease. Such changes likely result not only from changes within the brain but may occur at other levels, such as the autonomic nervous system.

Depression and Apathy

The first major type of emotional change in Parkinson’s disease involves changes such as depression and apathy.

These two terms are similar in some aspects, but not quite identical. The main difference, perhaps, is that people with depression usually feel sad or down. Apathetic people simply lack motivation to do things that they normally would enjoy.

The apathy in Parkinson’s disease may stem from some of the same problems with dopamine that causes movement problems in Parkinson’s disease. Dopamine is needed for the reward circuit that makes us feel good when we do something fun. Without that bonus, the drive to do things falls through. On the other hand, when dopamine is given to patients with Parkinson’s disease, some have the opposite problem, where they begin to engage in addictive behavior because the sense of reward is so strong.

Decreased Ability to Experience Emotion

Studies of emotional experience in Parkinson’s disease are usually performed by presenting stimuli with positive, negative, or neutral emotional valences.

Startle reflexes have also been assessed. In the face of such stimuli, subjective feeling and physiological arousal have both been suggested to be reduced in patients with Parkinson’s disease compared to healthy controls. Some authors suggest that individuals with PD suffer from alexithymia, an inability to identify one’s feelings.

Decreased Ability to Convey Emotion

People with Parkinson’s disease have been said to develop a “poker face.” There is less spontaneous smiling or frowning. Such decreased facial expression is called “amimia.” Conveying how we feel is important. The poker-face-like amimia of PD has been shown to likely impact interpersonal relationships, and also reduce quality of life.

It’s been long suspected that involuntary movements, such as those predominantly impacted by the BG network and involved in emotion. In a study by Smith and colleagues in 1996, Parkinson’s disease patients had reduced emotional facial responses to emotional stimuli, but could produce expression on command. Other studies, however, report deficits in voluntary emotional facial expression production alone, or in both spontaneous and voluntary emotional facial expression production in PD patients. None of these studies control for cognitive impairment or dopamine repletion, so the question remains somewhat open.

Like amimia, dysprosody has been widely reported in PD.

This means an inability to convey emotion in the voice. Like facial expression, many believe this is a purely motor, articulatory disorder, but in 2008 Möbes and colleagues found that PD did not differ from healthy controls in a non-emotional motor prosodic condition, but did so in the production of emotional prosody.

Decreased Ability to Recognize Others’ Emotions

In addition to reduced ability to recognize internal emotion, those with Parkinson’s have trouble recognizing emotions in others as conveyed by prosody and perhaps facial expression as well. Prosodic recognition seems to be more difficult, perhaps due to large demands on executive function. A large meta-analysis demonstrated that PD patients are more impaired in recognizing negative emotions such as anger, disgust, fear and sadness than relatively positive emotions such as happiness and surprise. This held true even after correcting for different levels of difficulty across emotions. This disability doesn’t seem to relate to motor disability or depression, though visuospatial and executive deficits may play a role, with a particular link between prosodic emotion recognition and working memory. There was no significant change noted between on and off dopa conditions.

Studies of emotion in Parkinson’s disease have met with discrepant results, which delayed detection of an overall trend. Such discrepancies largely result from confounding factors first with the emotional task at hand (targeted emotions, stimulus modalities, task type, instructions) and the second set concerns characteristics of PD patients themselves (medication status, depression, and cognitive ability). This makes comparisons between studies difficult. Apathy should also be considered as a potential confounding factor.

Tasks may bring forth contrasting patterns of emotion recognition—discrimination tasks which ask to tell different types of emotion apart reveal significantly greater deficits in facial emotion recognition, and identification tasks requiring naming reveal more deficits in prosodic emotion recognition. A more recent study, however, demonstrated that early PD patients perform more poorly when taking medication compared to off medications in emotional prosody recognition.

The exact nature and cause of emotional dysfunction in Parkinson’s disease is still being worked out. It was actually only fairly recently that the deficits were noted at all, as they were overshadowed by the more prominent movement disorders. Through research, a more complete view of those with Parkinson’s disease is emerging.

Sources: 

Gray HM, Tickle-Degnen L. A meta-analysis of performance on emotion recognition tasks in Parkinson's disease. Neuropsychology 2010;24:176-191.

Möbes J, Joppich G, Stiebritz F, Dengler R, Schroder C. Emotional speech in Parkinson’s disease. Mov Disord 2008;23:824–829.

Pèron J, Dondaine T, Le Jeune F, Grandjean D, Verin M. Emotional processing in Parkinson's disease: a systematic review. Movement disorders : official journal of the Movement Disorder Society 2012;27:186-199.

Pèron J, Grandjean D, Drapier S, Verin M. Effect of dopamine therapy on nonverbal affect burst recognition in Parkinson's disease. PloS one 2014;9:e90092.

Smith MC, Smith MK, Ellgring H. Spontaneous and posed facial expres- sion in Parkinson’s disease. J Int Neuropsychol Soc 1996;2:383–391.

Continue Reading